U.S. Pat. Nos. 5,433,289 (O'Rourke) and RE35,028 (Casebolt et al) both disclose safety harnesses with front D-rings. Most safety harnesses have a rear D-ring adapted for connection to a fall protection safety line. The addition of a front D-ring is a useful innovation that enables personnel to lean back with their weight supported by a safety line or climbing aid connected to the front D-ring. An example of the usefulness of the front D-ring is for transmission tower or ski lift maintenance personnel, who must climb long ladders. The addition of the front D-ring on the harness enables them to lean back with their weight supported by the front D-ring. This can provide respite when climbing up or down the access ladders.
Both the O'Rourke and Casebolt et al references have some inherent drawbacks. With the O'Rourke reference, the front D-ring has an associated friction buckle. The friction buckle allows the positioning of the front D-ring to be adjusted upwardly or downwardly. During use over time, this friction buckle has a tendency to creep upwardly. Should a fall occur which must be arrested by the front D-ring, the front D-ring tends to travel several inches before the friction buckle holds fast. The combination of gradual creep through use and travel when under load has negative consequences. There is a danger that the front D-ring will be positioned too high on the body when a fall is arrested, thereby bringing the safety line into contact with the wearer's face. Another problem with the O'Rourke reference relates to the structural integrity of the safety harness should one of the shoulder straps fail. A severed shoulder strap will pull through the friction buckle, leaving the wearer suspended by a single diagonal shoulder strap and potentially resulting in the wearer being dumped out of the harness. The friction buckle will not work effectively on the one remaining shoulder strap, the weight of the worker will result in the front D-ring moving up as high as possible.
The Casebolt et al reference has a single length of webbing which is wrapped around a cross piece on the front D-ring to form two shoulders straps with one strap extending over a wearer's left shoulder and another strap extending over a wearer's right shoulder. An adjuster link is provided. When adjuster link is spaced from the front D-ring the webbing can slide freely over the cross-piece on the front D-ring. When the adjuster link is positioned against the front D-ring, the adjuster link serves to lock the webbing in position. The adjuster link is more secure than the friction buckle of the O'Rourke reference described above, there is, therefore, a reduction in gradual creep through use and travel when under load. However, a problem remains with the Casebolt et al reference relating to the structural integrity of the safety harness should one of the shoulder straps fail. A severed shoulder strap will pull the single length of webbing through the cross piece of the adjuster link, leaving the wearer with no shoulder straps and potentially resulting in the wearer being dumped out of the harness.